Electrically controlled hand tool for friction-fusing non-metallic strap

ABSTRACT

A tool for friction-fusing overlapping strap portions including an electric motor for oscillating a rocker member, with the rocker member being connected to an output member for initially intermittently rotating a strap gripping member in a first direction to withdraw one strap portion, and further including a level for sensing tension in said one strap portion for converting the intermittent rotary motion of the output member into oscillating movement, whereby one strap portion is moved relative to the other strap portion to effect interface melting therebetween. The shaft of the electric motor has an eccentric portion integral therewith and a sleeve is slidably mounted thereon and received within a cavity in the rocker member. The cavity in the rocker member is generally semi-circularly shaped, and the sleeve has arcuate upper and lower portions that are seated within the cavity. A ratchet and pawl mechanism is provided for converting the intermittent rotary motion of the output member into oscillating movement, and actuation of the ratchet and pawl mechanism is controlled by the tension sensing lever which has a pawl latching portion formed integrally therewith that release the pawl when a predetermined amount of tension is drawn in one strap portion.

June 13, 1972 |,J,v|1 |Ns EI'AL 3,669,799

ELECTRICALLY GONTROLLED HAND TOOL FOR FRIGTIoN-FUSING NoN-METALLIC STRAP Filed June 16, 1970 S Sheets-Shut 1 l wg June 13, 1972 I. J. VILCINS ETAL ELECTRIC/hm( CONTROLLED HAND TOOL FOR FRIGTION-FUSING NON-METALLIC STRAP Filed June 16, 1970 3 Sheets-Shut 2 l@ 1 QAM, Wwf/dawn June 13, 1972 1, vlLclNs ETAL 3,669,799

ELEQTMCALLY CONTROLLED HAND Toor. FOR FRIGTIoN-FUSING NoN-METALLIC STRAP Filed June 16, 1970 5 Sheets-Shut 5 Patented June 13, 1972 3,669,799 ELECTRICALLY CONTROLLED HAND TOOL FOR FRICTlON-FUSING NON-METALLIC STRAP Ilmar J. Vilcius, Northbrook, and Robert J. Frey, Mount Prospect, Ill., assignors to Signode Corporation Filed June 16, 1970, Ser. No. 46,727 Int. Cl. B32b 3]/20 U.S. Cl. 156-359 9 Claims ABSTRACT OF THE DISCLOSURE A tool for friction-fusing overlapping strap portions including an electric motor for oscillating a rocker member, with the rocker member being connected to an output member for initially intermittently rotating a strap gripping member in a first direction to withdraw one strap portion, and further including a lever for sensing tension in said one strap portion for converting the intermittent rotary motion of the output member into oscilalting movement, whereby one strap portion is moved relative to the other strap portion to effect interface melting therebetween. The shaft of the electric motor has an eccentric portion integral therewith and a sleeve is slidably mounted thereon and received within a cavity in the rocker member. The cavity in the rocker member is generally semicircularly shaped, and the sleeve has arcuate upper and lower portions that are seated within the cavity. A ratchet and pawl mechanism is provided for converting the intermittent rotary motion of the output member into oscillating movement, and actuation of the ratchet and pawl mechanism is controlled by the tension sensing lever which has a pawl latching portion formed integrally therewith that releases the pawl when a predetermined amount of tension is drawn in one strap portion.

BACKGROUND OF THE INVEN'HON In the commonly assigned copending application of Arvid I. Ericsson, Ser. No. 801,133 entiltled Electrically Controlled Hand Tool For Friction-Posing Non-Metallic Strap, now U.S. Pat. No. 3,586,572, an extremely novel portable and lightweight tool is disclosed and claimed. The apparatus disclosed in the Ericsson application includes a novel drive means for a strap gripping member which includes an electrim motor having eccentric means coupled to the output shaft thereof to oscillate a rocker arm member. The rocker arm is coupled to the shaft of the gripping member through a one way clutch, so that the gripping member is initially rotated in a tirst direction to draw a predetermined amount of tension in the strap loop. The one way clutch transmits intermittent rotary motion to the gripping member, but the intermittent rotary motion is at such a fast rate as to appear continuous. When the selected amount of tension is drawn in the loop, a ratchet and pawl mechanism is engaged to block rotation of the gripping member, so that the rocker arm oscillates the gripping member at a frequency and amplitude sucient to cause interface melting between the frictionally engaged interface regions of the overlapping strap portions.

In the apparatus illustrated in the Ericsson application, a sleeve having an eccentric portion is mounted on the output shaft of the motor, and a slide block is mounted on the eccentric portion of the sleeve. The slide block includcs a transverse opening that is impaled by a pin which extends between openings in rearwardly extending arms of the rocker member. While this arrangement has functioned satisfactorily to provide a connection between the drive motor and the rocker member, it is somewhat complicated and necessitates an undesirably large number of parts.

In the arrangement illustrated in the Ericsson application, a blocking element engages the pawl of the pawl and ratchet mechanism to normally retain the pawl out of er1- gagement with the ratchet so that the output member is free to rotate intermittently as described above. A release lever is pivotally mounted within the tool, and includes a hook-like detent that engages an abutment on the blocking element to retain the blocking element in a position holding the pawl out of engagement with the ratchet. A spring is provided to bias the detent of the release lever into engagement with the abutment on the blocking element, and the release lever is pivoted against the bias of the spring to free the blocking element in response to movement of the tension sensing lever. While this arrangement has functioned satisfactorily, the relatively large number of parts make it somewhat undesirable from a manufacturing and maintenance viewpoint.

SUMMARY OF THE INVENTION The present invention constitutes an improvement upon the drive means of the apparatus illustrated in the above mentioned Ericsson application. In the structure of the present invention, the shaft of the drive motor includes an eccentric portion integral therewith that has a sleeve slidably mounted thereon. A single rearwardly extending arm on a rocker member has a generally semi-circularly shaped cavity therein, and the sleeve has arcuate upper and lower surfaces that are seated within the cavity. The tension sensing lever in the present invention includes a detent portion integral therewith that engages an abutment on a blocking element that normally retains the pawl of the ratchet and pawl mechanism out of engagement with the ratchet until an appropriate amount of tension has been drawn in the strap loop. The invention of the present application is a significant improvement upon the structure illustrated in the Ericsson application, since it eliminates a plurality of parts heretofore thought necessary, without eliminating the function of these parts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a friction-fusion tool in a sealing position on a package, with a strapping ligature having been formed into a loop about the package;

FIG. 2 is an enlarged view taken generally along line 2-2 of FIG. l;

FIG. 3 is a view taken generally along line 3-3 of FIG. 2;

FIG. 4 is a schematic wiring diagram of the control system of the present invention;

FIG. 5 is a sectional view taken generally along line 5 5 of FIG. 2; and

FIG. 6 is a sectional view taken generally along line 6-6 of FIG. 2.

DETAILED DESCRIPTION While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail only a preferred embodiment of the invention, with the understanding that the present disclosure is to be considered as an exempliication of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

Referring now to the drawings in detail, a frictionfusion tool is shown generally at 10 in the drawings, and tool 10 includes a frame in the form of a housing defined by mating housing members 11 and 12 secured together by screws 13. A handle 14 is provided at the upper end of tool 10, and handle 14 is formed of inverted U-shaped handle portions 15 and 16 formed integrally with housing members 11 and 12, respectively. Housing members 11 and 12 are generally thin walled shell-like structures, which collectively define a hollow interior or chamber 17 therebetween.

The tool is shown in position on a package P in FIG. 1, with the trailing end portion 18 of a loop L of thermoplastic strap overlapping a leading end portion 19 of the strap, and with the overlapping strap portions being positioned between a strap gripping wheel 20 and a strap supporting anvil 21. The trailing strap end portion 18 may extend to a suitable supply of strap, not shown. Drive means, to be hereafter described in detail, is provided within the chamber 17 of tool 10 for shifting anvil 21 upwardly into strap compressing relationship with respect to wheel 20, for intermittently rotating wheel 20 to withdraw the upper strap portion 18 to the right, as viewed in FIG. l, to constrict the loop L about the article and place the loop in tension, and for oscillating wheel 20 relative to anvil 21 to produce bodily sliding frictional movement between the opposing surface regions of the overlapping strap portions 18 and 19 to effect interface melting therebetween.

The drive means within chamber 17 includes an electric motor M (FIG. 2), and motor M includes a rotary out put shaft 23, the left-hand end of which is supported in a bearing 24 in the rear wall of the housing, and the forward end of which is supported in a bearing 25 that is provided in an intermediate housing wall 26. The right-hand end 27 of shaft 23 includes an integral eccentric portion 30. Shaft portion 30 extends through a bore 31 in a slide block 32, and block 32 is mounted for lateral sliding movement within a transversely extending, generally cylindrically shaped cavity 33 in the rearwardly extending arm 41 of a rocker member 40. Slide block 31 includes rounded upper and lower surfaces that make slidable engagement within cavity 33.

Thus, when motor M is energized eccentric shaft portion 30 moves along a circular path concentric with the axis of the shaft, and block 32 is moved up and down, and from side to side within cavity 33. As will hereinafter appear, because of the fixed location of the shaft of gripping wheel 20, block 32 also moves axially along eccentric portion 30. The rocker is driven by eccentric shaft portion 30, and rocker 40 is mounted for oscillating movement relative to the frame about an axis defined by the shaft of gripping wheel 20, shaft 45 being rotatable supported in housing members 11 and 12 by bearings 46 and 47, respectively. Thus, as block 32 is moved up and down by eccentric portion 30, rocker arm 40 oscillates about the axis of shaft 45, and the slidable mounting of block 32 on eccentric portion 30 allows the block 32 to shift axially during this movement.

Rocker member 40 includes a generally annularly shaped wall 52 that defines a chamber 53 therewithin. A ratchet wheel 54 is provided within chamber 53, and a ratchet wheel 54 is provided with a central hexagonally shaped opening 55 that is slidably positioned over a hexagonally shaped shaft portion 50. The ratchet teeth around the periphery of wheel 54 cooperate with a pawl mechanism to be hereafter described for converting intermittent rotary motion of the shaft 45 to osciallating motion.

Shaft 45 further includes a portion 58 of enlarged diameter forwardly of shaft portion 50, and the transition between these shaft portions degfnes a rearwardly facing shoulder that confines the ratchet wheel 54 against the adjacent planar rocker arm surface 48. The strap gripping wheel 20 is provided at the outer end of shaft portion 58.

lA one way clutch mechanism is provided in chamber 53 for converting the oscillating movement of rocker member 40 into intermittent rotary motion of ,shaft 45, and in the illustrated embodiment, the one way clutch mechanism takes the form of a plurality of inwardly facing clutch teeth 66 which trap cylindrically shaped rollers 67 therebetween. Teeth 66 are shaped so as to allow the rocker member 40 to rotate freely in a counterclockwise direction (FIG. 2) relative to the shaft portion 58, but when the rocker member 40 is rotated in a clockwise direction, the rollers 67 bind the teeth 66 and the shaft portion 58 to rotate the shaft 45 and gripping wheel 20 in a tension drawing direction.

Means is provided for sensing when a predetermined amount of tension has been drawn in strap loop L, and the tension sensing means includes a fiat plate-like lever 70 (FIG. 2) having outwardly extending tabs 71 at opposite side thereof received in axially aligned clearance openings 72 in housing members 11 and 12. Lever 70 includes a tension 4sensing nger 75 that extends outwardly of housing member 12 through an opening 76 therein, and nger 75 overlies anvil 21 with the overlapping strap portions `18 and 19 being disposed beiow finger 75. After a predetermined amount of tension has been drawn in the loop L, the upper portion 18 of the strap snaps upwardly to pivot the lever 70 upwardly.

The pivotal movement of lever 70 is resisted by a spring 81 (FIG. 3) that is positioned in a vertical bore 82 in housing member 12, and the force that spring 81 applies to lever 70 may be adjusted by a set screw 83 that is received in the internally threaded upper end of bore 82. In this manner, the amount of tension in the loop L that is sufficient to pivot the lever 70 can be preselected, so that the tautness of the loop L around the package P can be varied, as desired.

Before proceeding with a detailed description of the means for converting the intermittent rotary motion of shaft 45 to oscillating movement, the means for effecting relative movement between strap gripping wheel 20 and anvil 21 to compress the overlapping strap portions 18 and 19 will be described. In the present embodiment of the invention, the anvil 21 is movable upwardly toward the strap gripping wheel 20, and to this end, the anvil 21 is formed as an outwardly extending shelf at the lower end of a vertically disposed base member 85. Base member 85 includes an enlarged non-circular opening 86 that is positioned over shaft portion 58 to enable the base member 85 to move relative to the shaft 45. The means for shifting plate `85 includes a shaft 88 (FIGS. 2 and 5) that is rotatably journaled in frame members 11 and 12 above shaft 45. A torsion spring 89 surrounds shaft 88, and one end 90 of spring 89 bears against housing member 12, while the opposite end 91 of spring 89 extends through shaft 88 (FIG. 2) to bias the shaft 88 in a clockwise direction.

An eccentric pin 92 (FIG. 5) extends outward from shaft 88, and pin 92 extends outwardly of frame member 12 where it is rotatably journaled in an opening 87 at the upper end of plate 85. Plate 85 includes an inwardly bent arm `93 that extends inwardly of housing member 12 through an opening 94 (FIGS. 2 and 6), and the lower end of arm 93 is provided with an inclined cam surface 95 for a purpose to hereafter appear. Arm portion 93 functions as a blocking element `preventing oscillation of the gripping wheel 20 until the anvil 21 has moved into `strap compressing relationship with respect to the gripping wheel 20, and tension has been drawn in the strap loop L, as will also hereinafter appear.

A return lever has a mounting portion fixed to shaft 88 between plate 85 and housing member 12, and lever 100 has a detent surface 102 (FIG. 1) that is adapted to be retentively engaged by a hook (not shown) on a cutter handle 104. Cutter handle 104 is pivotally mounted upon member 8S at 106, and handle 104 includes an arcuate camming surface, not shown, that is engageable with an abutment on a cutter element 105 that is pivotally mounted upon base plate 85 at 107. A knife edge is provided at the lower end of cutter element 105 and the cutting edge severs the upper strap portion 18 when the cutter element is pivoted in a counterclockwise direction, as viewed in FIG. l, by handle 104 against the bias of a return spring, not shown. When handle 104 is pivoted to disengage the hook on handle 104 from detent 102 on handle 100, torsion spring 89 rotates shaft 88 to swing the lever 100, and the action of eccentric pin 92 lifts plate 85 to bring the anvil 21 into 4strap compressing relationship with respect to gripping wheel 20.

After the anvil 21 has been moved into strap compressing relationship with gripping wheel 20, and the preselected amount of tension has been drawn in the strap loop L through the intermittent rotation of gripping wheel 20, the aforedescribed lever 70 pivots upwardly and a hooked pawl release portion 110 integral with lever 70 moves out of retentive engagement with an inwardly curved detent i115 on a pawl reset lever 116. Pawl reset lever 1116 includes outwardly extending fingers 118 at opposite ends thereof that are received in openings 119 in housing members L1 and 12, with openings 119 being oversized (FIG. 2) to accommodate rocking movement of the latch reset member 116. Lever `116 includes an upwardly extending portion 122 positioned to engage the pawl 130 for resetting the same, and lever 116 further includes an inclined cam surface 123 that is adapted to be engaged by cam surface 95 on plate 85 for repositioning the pawl 130, as will hereinafter appear.

Pawl 130 is pivotally mounted on a transversely extending pin 131, and the pawl includes a first arm 132 having a toothed end portion positioned to engage the teeth on ratchet wheel 54, and a second end portion 133 positioned to engage the upstanding portion 122 of lever 116. A spring 134 acts between a recess in pawl arm 133 and a recess in the side wall of rocker member 40 for biasing the pawl 130 in a counterclockwise direction, as viewed in FIG. 2. Thus, after the anvil 21 has been raised, finger 93 on plate 85 is moved upwardly and the cam surface 95 on finger 93 is spaced above cam surface 123 on lever 116 to condition the pawl 130 for movement into engagement with the ratchet wheel 54. After tension has been drawn in the strap loop L, lever 70 is moved upwardly to free hook 110 from linger 115 on level 116 and spring 134 biases lever 116 outwardly to position cam surface 123 below cam surface 95. Concurrently with the movement of lever 116, spring 134 pivots pawl 130 to bring the toothed end 132 of the pawl into engagement with the teeth on ratchet wheel 54, and this engagement prevents the ratchet wheel 54 and shaft 45 from rotating in a clockwise direction, as viewed in FIG. 2.

Thus, when the appropriate tension has been attained in the strap loop L, one way clutch means 65 cooperates to prevent shaft 45 from rotating in a counterclockwise direction, while pawl 130 prevents shaft 45 from rotating in a clockwise direction. Accordingly, as rocker arm 40 continues to oscillate, shaft 45 is efectively'locked to the rocker arm, and strap gripping wheel 20 is oscllated in a high frequency-low amplitude mode to move the upper strap portion 18 multi-directionally relative to lower strap portion 19.

A control system for regulating the length of time that motor M is retained energized to thereby regulate the overall length of the tension drawing and friction-fusing operations is disclosed herein, and is claimed in the concurrently led, commonly assigned application of Robert l. Frey, entitled Control System for Apparatus for Friction-Fusing Overlapping Portions of a Thermoplastic Strapping Ligature. The control system includes first and second control means in the form of switches 162 and 164 that are connected in a series circuit with motor M. Switches 162 and 164 are mounted alongside one another within the cavity 17 of tool 10, as can be best seen in FIG. 2. Switches 162 and 164 are both of the single-pole, double-throw variety, with switch 162 including an actuating lever 166, and switch 164 including an actuating lever 168. Switch lever 166 is normally held in a closed position against contact 162a by a spring 170 that is provided internally of switch 162. Switch lever 168 is normally retained in an open position against 6 contact 164a, by a spring 172 that is provided internally of switch 164.

A common operating means 174 is provided for moving the switch levers 166 and 168 toward engagement with contacts 162b and 164b, respectively, and operating means 174 will be best understood from a consideration of FIG. 3. The common operating means 174 is defined by a push button 176 that is mounted for reciprocating movement within a cylindrical recess 178 in housing member 11. The push button 176 includes a manually engageable cap portion 180 having an annular recess 182 therein that provides a seat for one end of a coil spring 184. A body member 186 is snap fit within a central bore 188 in cap portion 180 and extends through an opening in a wall 192 that extends transversely relative to wall 178. Body member 186 includes an enlarged head 190 at one end thereof that is held in engagement with wall 192 by spring 184.

A connector member 194 is fixed to switch lever 166, as by spot welding as shown at 195 in FIG. 2, and the opposite end of connector member 194 overlaps switch lever 168 in alignment with push button head portion 190. Thus, when the push button 176 is moved inwardly from the position of FIG. 3 against the bias of spring 184, connector member 194 simultaneously causes switch levers 166 and 168 to move away from contacts 162a and 1640, respectively. When switch levers 166 and 168 move into engagement with contacts 162b and 164b, respectively, and push button 176 is released so that spring 184 returns the push button to the position of FIG. 3, spring 170 returns switch lever 166 into engagement with contact 162a. Timer means 196 is connected to switch lever 168 and retains the same in engagement with contact 164b for a fixed time interval even though the push button 176 has been returned to the position of FIG. 3.

With switch lever 166 in engagement with contact 162a and switch lever 168 in engagement with contact 164b, a series circuit is completed to motor M `by lines 198 and 200 that are connected to a 11S-volt 60 cycle source of alternating current. It will be understood that the motor M will remain energized for the length of time that the timer means 196 retains the switch lever 168 in engagement with contact 164b, and that when the switch contact 168 moves into engagement with contact 164s, the circuit to the motor M will be opened to de-energize the motor.

While many different types of timer means may be provided for controlling switch 164, an air dashpot timer of the type illustrated and described in Product Data Buletin #675 of Magnecraft Electric Co., 5575 North Lynch Ave., Chicago, Ill., has been found to Abe extremely well suited for the tool illustrated herein. As is set forth in the above mentioned bulletin, the air dashpot timer 196 includes a piston 202 that is movable within a cylinder 204, with the rod end 206 of the piston being connected to the lever 168 of switch 164, as by a fastener 208. Timer 196 is supported in a cylindrical wall 210 of housing member 12. and an adjusting screw 212 (FIG. 3) is accessible through an opening 214 in housing member 12 for controling a needle valve (not shown) that regulates the rate of air bleed into the cylinder 204 to thereby control the length of time that the timer 196 retains switch lever 168 in the closed position in engagement with contact 164b.

In an exemplary embodiment of the invention, the motor M is retained energized for approximately one second, although periods of energization within the range of 3A of a second to 11/2 seconds have produced satisfactory friction-fusion joints. The aforementioned time intervals include the overall length of time to withdraw the slack from loop L by the intermittent rotary motion of gripping wheel 20 and the length of time to achieve interface melting by the oscillating movement of wheel 20. The take up of slack in the loop L occurs extremely rapidly, and is normally only a matter of a few inches.

Because of the short length of time required to tension the loop, and since this time period would be consistent with a given operator, it does not significantly influence the timing required to effect the interface melting. Since the timer 196 is adjustable, the timing thereof can be varied to tit any given operator technique.

What is claimed is:

1. A friction-fusion strap sealing tool comprising: frame means defining an enclosure; first and second strap gripping members positioned in juxtaposed relation outwardly of said frame means; means for effecting relative movement between said strap gripping members to move them into and out of strap compressing relationship with respect to overlapping strap portions positioned therebetween; and a drive mechanism within said enclosure, said drive mechanism including an input member having an eccentric portion, means for rotating said input member, an output member having said first gripping member thereon, a rocker member, means connecting said rocker member to said output member for intermittently rotating said output member in one direction, means connecting said rocker member to said input member, said last named means including an arm on said rocker member extending toward said eccentric portion and a sleeve mounted on said eccentric portion, said arm having a generally arcuate cavity therein facing said eccentric portion, said sleeve being slidably mounted on said eccentric portion and having curved surfaces seated within said cavity to mount said sleeve for lateral movement relative to said arm, whereby upon rotation of said input member said sleeve oscillates said rocker member and said connecting means intermittently rotates said output member and said first gripping member, and means for converting the intermittent rotating movement of said output member to oscillating movement for oscillating said first gripping member and the strap portion engaged thereby rectilinearly.

2. A friction-fusion strap sealing tool as set forth in claim 1 in which said input member is a motor shaft, and wherein said eccentric portion is formed integrally with said shaft.

3. A friction-fusion strap sealing tool as set forth in claim 2 in which said motor shaft is inclined downwardly toward said rocker member.

4. A friction-fusion strap sealing tool as set forth in claim 1 in which said cavity is generally semi-circularly shaped, and wherein said sleeve has rounded por l opposite ends thereof on a radius substantially the same as that of said cavity to provide said curved surfaces.

5. A friction-fusion strap sealing tool as set forth in claim 1 in which said connecting means includes clutch means connected between said rocker member and said output member, and wherein said converting means is a ratchet and pawl mechanism for preventing rotation of said output member in said one direction when the ratchet and pawl of said mechanism are engeged.

6. A friction-fusiion strap sealing tool as set forth in claim S including a tension sensing lever pivotally mounted within said enclosure, said lever having an arm extending outwardly of said frame means into position to be engaged by a strap portion for pivoting said lever when the intermittent rotating movement of said first gripping member draws a predetermined amount of tension in said strap, a blocking element within said enclosure and engageable with said pawl for holding said pawl out of engagement with said ratchet until said predetermined amount of tension is drawn, said blocking element having an abutment thereon, a detent integral with said tension sensing lever and engageable with said abutment for releasably retaining said blocking element in a position holding said pawl out of engagement with said ratchet, and means for moving said pawl into engagement with said ratchet when said tension sensing lever is pivoted to move said detent out of engagement with said abutment.

7. A friction-fusion strap sealing tool comprising: frame means defining an enclosure; first and second strap gripping members positioned in juxtaposed relation outwardly of said frame means; means for effecting relative movement between said strap gripping members to move them into and out of strap compressing relationship with respect to overlapping portions of a strap loop positioned therebetween; and a drive mechanism within said enclosure, said drive mechanism including an input member, means for rotating said input member, an output member having said first gripping member thereon, a rocker member, means connecting said input member to said rocker member for oscillation of said rocker member upon rotation of said input member, means connecting said rocker member to said output member for intermittently rotating said output member in one direction so that said first gripping member moves one strap portion in a direction to tension said loop, ratchet and pawl means for preventing rotation of said output member in said one direction, a tension sensing lever pivotally mounted within said enclosure, said le'ver having an arm extending outwardly of said enclosure into position to be engaged by said loop for pivoting said lever when a predetermined amount of tension is drawn therein by rotation of said first gripping member, a blocking element within said enclosure and engageable with said pawl for holding said pawl out of engagement with said ratchet until said predetermined amount of tension is drawn, said blocking element having an abutment thereon, a detent integral with said tension sensing lever and engageable with said abutment for releasably retaining said blocking element in a position holding said pawl out of engagement with said ratchet, and means for moving said pawl into engagement with said ratchet ywhen said tension sensing lever is pivoted to move said detent out of engagement with said abutment, whereby said first gripping member and the strap portion en gaged thereby are oscillated rectilinearly.

8. A friction-fusion strap sealing tool as set forth in claim 7 wherein said tension sensing lever is a fiat platelike member having a first side and a second side, axially aligned projections extending outwardly from said first A cogrsidwsides and received in axially aligned passages in sai ramn'iwnsto pivotally mount said lever.

9. A friction-fusion strap sealing tool as set forth in claim 8 in which the abutment on said blocking mem-ber extends upwardly and toward the axis of the projections of said lever, said detent being provided by a notched portion of said lever that faces downwardly and away from the axis of said projections into a position to releasably retain the projection therewithin.

References Cited UNITED STATES PATENTS 3,442,734 5/l969 Ericsson 156-73 3,442,733 5/1969 Vilcins 156-73 3,442,732 5/1969 Stensaker 156-73 3,554,846 l/l971 Billett 156-73 BENJAMIN A. BORCHELT, Primary Examiner J. V. DORAMUS, Assistant Examiner U.S. Cl. X.R. 156-73 

